Packer end ring with device for gripping base pipe

ABSTRACT

A packer can include an end ring positioned proximate a seal element on a base pipe, and a gripping device which is compressed radially inward by a surface formed in the end ring, the surface encircling the base pipe. A method of constructing a packer can include positioning an end ring on a base pipe proximate a seal element, and radially compressing a gripping device in the end ring, so that the gripping device grips the base pipe, radial compression of the gripping device resulting from longitudinal displacement of the gripping device relative to the end ring.

TECHNICAL FIELD

This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in one example described below, more particularly provides a packer end ring with a device for gripping a base pipe.

BACKGROUND

Packers are used in wells to seal off annuli formed between tubular strings, or between a tubular string and another surface, such as a wall of a wellbore. It is important to construct packers so that they can reliably withstand substantial differential pressure, but it is also important to construct packers in an economical and expeditious manner.

Therefore, it will be appreciated that improvements are continually needed in the art of constructing packers for use in wells.

SUMMARY

In this disclosure, systems and methods are provided which bring improvements to the art of constructing packers. An example is described below in which a gripping device is contained in an end ring, so that the gripping device grips a base pipe and prevents longitudinal displacement of a seal element relative to the base pipe.

An improved packer is provided to the art in the disclosure below. In one example, the packer can comprise an end ring positioned proximate a seal element on a base pipe, and a gripping device which is compressed radially inward by a surface formed in the end ring, the surface encircling the base pipe.

Also described below is a method of constructing a packer. In one example, the method can include: positioning an end ring on a base pipe proximate a seal element; and radially compressing a gripping device in the end ring, so that the gripping device grips the base pipe. Radial compression of the gripping device results from longitudinal displacement of the gripping device relative to the end ring.

Also described below is a packer which can comprise an end ring positioned proximate a seal element on a base pipe, and a circular gripping device which encircles the base pipe and is compressed radially inward by a surface formed in the end ring.

These and other features, advantages and benefits will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the disclosure below and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representative cross-sectional view of a well system and associated method which can embody principles of this disclosure.

FIG. 2 is an enlarged scale representative cross-sectional view of a packer which may be used in the system and method of FIG. 1, and which can embody the principles of this disclosure.

FIG. 3 is a further enlarged scale representative cross-sectional view of a portion of the packer.

FIG. 4 is an end view of an end ring of the packer.

FIG. 5 is a cross-sectional view of the end ring, taken along line 5-5 of FIG. 4.

DETAILED DESCRIPTION

Representatively illustrated in FIG. 1 is a system 10 for use with a subterranean well, and an associated method, which can embody principles of this disclosure. However, it should be clearly understood that the system 10 and method are merely one example of an application of the principles of this disclosure in practice, and a wide variety of other examples are possible. Therefore, the scope of this disclosure is not limited at all to the details of the system 10 and method described herein and/or depicted in the drawings.

In the FIG. 1 example, a packer 12 is interconnected in a tubular string 14 and positioned in a wellbore 16. The packer 12 includes a seal element 18 which extends radially outward into sealing engagement with the wellbore 16, thereby sealing off an annulus 20 formed radially between the tubular string 14 and the wellbore 16.

In this example, the wellbore 16 is lined with casing 22 and cement 24. In other examples, the wellbore 16 could be uncased or open hole, in which case the seal element 18 could sealingly engage a wall 26 of an earth formation 28 penetrated by the wellbore 16.

The seal element 18 can comprise a swellable material which swells in response to contact with a particular fluid in the well. The term “swell” (and similar terms, such as, “swellable,” “swelling,” etc.) is used herein to indicate an increase in volume of a material. A seal element can expand outward without swelling (e.g., as in inflatable or compression-set packers, etc.). However, the seal element material itself increases in volume if the material is to be considered swollen.

Preferably, the swellable material swells when it is contacted with a particular swelling fluid (e.g., oil, gas, other hydrocarbons, water, etc.) in the well. The swelling fluid may already be present in the well, or it may be introduced after installation of the packer 12 in the well, or it may be carried into the well with the packer, etc. The swellable material could instead swell in response to exposure to a particular temperature, or upon passage of a period of time, or in response to another stimulus, etc.

End rings 30 longitudinally straddle the seal element 18 on a base pipe 32, in order to restrict longitudinal displacement of the seal element on the base pipe. In most situations, it is desired for the end rings 30 to substantially prevent any displacement of the seal element 18 relative to the base pipe 32, so that a desired differential pressure can be sealed against in the annulus 20.

The end rings 30 may directly abut opposite longitudinal ends of the seal element 18 as depicted in FIG. 1. In other examples, components such as backup rings, etc. may be interposed between the end rings 30 and the seal element 18.

In further examples, multiple seal elements 18 could be straddled by the end rings 30, and an end ring could be positioned between a pair of seal elements. Thus, it should be clearly understood that the scope of this disclosure is not limited at all to any of the details of the packer 12, or seal element 18, end rings 30 and base pipe 32, as illustrated in the drawings or described herein.

Referring additionally now to FIG. 2, an enlarged scale cross-sectional view of the packer 12, apart from the remainder of the FIG. 1 system 10, is representatively illustrated. The packer 12 could, however, be used in other systems and methods, in keeping with the scope of this disclosure.

In this view, it may be seen that the seal element 18 comprises a swellable seal material 34, and encircles the base pipe 32. The base pipe 32 may be provided with end connectors (not shown) for interconnecting the packer 12 in the tubular string 14.

The end rings 30 are positioned at opposite ends of the seal element 18. The end rings 30 can serve to protect the seal element 18 as the packer 12 is being conveyed into the wellbore 16, as well as to prevent displacement of the seal element 18 relative to the base pipe 32.

In the FIG. 2 example, a gripping device 36 is positioned in each of the end rings 30. The gripping devices 36 secure the end rings 30 against longitudinal displacement relative to the base pipe 32, so that the seal element 18 is also secured against longitudinal displacement relative to the base pipe.

A further enlarged scale cross-sectional view of a portion of the packer 12 is representatively illustrated in FIG. 3. In this view, further details of the end ring 30 and gripping device 36 may be more clearly seen.

The end ring 30 has a frusto-conical interior surface 38 formed therein. The surface 38 tapers radially inward in a direction toward the seal element 18.

The gripping device 36 also has a frusto-conical surface 40 formed thereon. The surface 40 complementarily engages the surface 38, so that, if the gripping device 36 is displaced longitudinally toward the seal element 18, the gripping device will be compressed radially inward. Conversely, if the end ring 30 is displaced longitudinally away from the seal element 18, the gripping device 36 will be compressed radially inward by the cooperative action of the inclined surfaces 38, 40.

Note that it is not necessary for the surfaces 38, 40 to be frusto-conical. They could instead be inclined or curved, etc., in any other manner. Any means of radially compressing the gripping device 36 may be used, in keeping with the scope of this disclosure.

At least one of the gripping device and end ring surfaces 40, 38 can be provided with a friction reducing material to thereby reduce a biasing force required to displace the gripping device 36 longitudinally relative to the end ring 30. This will increase the gripping engagement between the gripping device 36 and the base pipe 32. Friction-reducing materials such as PTFE, ceramic coatings, etc., may be used, if desired.

When the gripping device 36 is radially compressed, a gripping surface 42 in the gripping device engages and grips an external surface 44 on the base pipe 32. The gripping surface 42 can have a coating, gripping particles, teeth, or any other treatment to enhance the gripping engagement between the surfaces 42, 44.

When the gripping device 36 engages the external surface 44 on the base pipe 32, the gripping device also closes off a radial gap between the end ring 30 and the base pipe. This can prevent extrusion of the seal element 18 through the gap, which can increase a differential pressure resisting capability of the packer 12.

Referring additionally now to FIGS. 4 & 5, the end ring 30 and gripping device 36 are representatively illustrated, apart from the packer 12. The end ring 30 and gripping device 36 may be used with packers other than the packer 12, in keeping with the scope of this disclosure.

In these views it may be more clearly seen that threaded members 46 are threaded into the end ring 30, in order to displace the gripping device 36 longitudinally relative to the end ring, thereby compressing the gripping device radially inward.

Although ten of the threaded members 46 are depicted in FIG. 4, any number may be used, as desired. As another example, a single ring-shaped threaded member could be threaded into the end of the end ring 30 to displace the gripping device longitudinally relative to the end ring. Thus, it should be understood that the scope of this disclosure is not limited at all to the details of the end ring 30, gripping device 36 or threaded members 46 as depicted in the drawings or described herein.

The threaded members 46 are illustrated as comprising externally-threaded socket head set screws. However, any other type of threaded member(s) may be used, as desired, and it is not necessary in keeping with principles of this disclosure, for the threaded members to be used at all. For example, the gripping device 36 could be biased relative to the end ring 30 by a biasing device (such as a spring, a swellable material, etc.).

In the FIG. 5 example, the gripping device 36 is annular shaped, so that it can encircle the base pipe 32, but the gripping device has at least one longitudinal split 48 therein, allowing the gripping device to be compressed radially inward. If one split 48 is used, the gripping device 36 may comprise a single circular segment which is resilient, so that it exerts an initial “bite” into the base pipe 32 when it is installed thereon. If multiple splits 48 are used, the gripping device 36 may comprise multiple circular segments which can readily conform to a misshaped (e.g., non-cylindrical, elliptical, rough, etc.) external surface 44 on the base pipe 32.

It may now be fully appreciated that the above disclosure provides significant advances to the art of constructing packers for use with a well. In examples described above, the end rings 30 and gripping devices 36 can effectively contain the seal element 18 on the base pipe 32, while being economical to manufacture and convenient to install.

The above disclosure provides to the art an improved packer 12. In one example, the packer 12 can comprise an end ring 30 positioned proximate a seal element 18 on a base pipe 32, and a gripping device 36 which is compressed radially inward by a surface 38 formed in the end ring 30. The surface 38 encircles the base pipe 32.

The surface 38 may be a frusto-conical surface. The gripping device 36 may grip the base pipe 32 in response to longitudinal displacement of the gripping device 36 relative to the surface 38.

The seal element 18 can include a swellable material 34 which swells in response to contact with a fluid.

The gripping device 36 may close off a gap formed radially between the base pipe 32 and the end ring 30.

The gripping device 36 can comprise a circular segment having a split 48 therein which permits radial compression of the circular segment. The gripping device 36 can comprise multiple circular segments.

A gripping surface 42 may be formed on the gripping device 36. At least one member 46 may thread into the end ring 30 and thereby radially compress the gripping device 36.

The gripping device 36 may include a surface 40 which cooperatively engages the end ring surface 38, and at least one of the gripping device and end ring surfaces 40, 38 can be provided with a friction reducing material.

A method of constructing a packer 12 is also described above. In one example, the method can include: positioning an end ring 30 on a base pipe 32 proximate a seal element 18, and radially compressing a gripping device 36 in the end ring 30, so that the gripping device 36 grips the base pipe 32. Radial compression of the gripping device 36 results from longitudinal displacement of the gripping device 36 relative to the end ring 30.

A packer 12 example described above can comprise an end ring 30 positioned proximate a seal element 18 on a base pipe 32, and a circular gripping device 36 which encircles the base pipe 32 and is compressed radially inward by a surface 38 formed in the end ring 30.

Although various examples have been described above, with each example having certain features, it should be understood that it is not necessary for a particular feature of one example to be used exclusively with that example. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the examples, in addition to or in substitution for any of the other features of those examples. One example's features are not mutually exclusive to another example's features. Instead, the scope of this disclosure encompasses any combination of any of the features.

Although each example described above includes a certain combination of features, it should be understood that it is not necessary for all features of an example to be used. Instead, any of the features described above can be used, without any other particular feature or features also being used.

It should be understood that the various embodiments described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of this disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments.

In the above description of the representative examples, directional terms (such as “above,” “below,” “upper,” “lower,” etc.) are used for convenience in referring to the accompanying drawings. However, it should be clearly understood that the scope of this disclosure is not limited to any particular directions described herein.

The terms “including,” “includes,” “comprising,” “comprises,” and similar terms are used in a non-limiting sense in this specification. For example, if a system, method, apparatus, device, etc., is described as “including” a certain feature or element, the system, method, apparatus, device, etc., can include that feature or element, and can also include other features or elements. Similarly, the term “comprises” is considered to mean “comprises, but is not limited to.”

Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of this disclosure. For example, structures disclosed as being separately formed can, in other examples, be integrally formed and vice versa. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the invention being limited solely by the appended claims and their equivalents. 

What is claimed is:
 1. A packer, comprising: an end ring positioned proximate a seal element on a base pipe; and a circular gripping device which encircles the base pipe and is compressed radially inward by a surface formed in the end ring.
 2. The packer of claim 1, wherein the surface comprises a frusto-conical surface.
 3. The packer of claim 1, wherein the gripping device grips the base pipe in response to longitudinal displacement of the gripping device relative to the surface.
 4. The packer of claim 1, wherein the seal element comprises a swellable material which swells in response to contact with a fluid.
 5. The packer of claim 1, wherein the gripping device closes off a gap formed radially between the base pipe and the end ring.
 6. The packer of claim 1, wherein the gripping device comprises a circular segment having a split therein which permits radial compression of the circular segment.
 7. The packer of claim 1, wherein the gripping device comprises multiple circular segments.
 8. The packer of claim 1, further comprising a gripping surface formed on the gripping device.
 9. The packer of claim 1, further comprising at least one member which threads into the end ring and thereby radially compresses the gripping device.
 10. The packer of claim 1, wherein the gripping device comprises a surface which cooperatively engages the end ring surface, and wherein at least one of the gripping device and end ring surfaces is provided with a friction reducing material.
 11. A method of constructing a packer, the method comprising: positioning an end ring on a base pipe proximate a seal element; and radially compressing a gripping device in the end ring, so that the gripping device grips the base pipe, radial compression of the gripping device resulting from longitudinal displacement of the gripping device relative to the end ring.
 12. The method of claim 11, further comprising the seal element swelling in response to contact with a fluid in a well.
 13. The method of claim 11, further comprising the gripping device closing off a gap formed radially between the base pipe and the end ring.
 14. The method of claim 11, wherein the gripping device comprises a circular segment having a split therein which permits radial compression of the circular segment.
 15. The method of claim 11, wherein the gripping device comprises multiple circular segments.
 16. The method of claim 11, wherein a gripping surface is formed on the gripping device, and wherein the radially compressing comprises engaging the gripping surface with the base pipe.
 17. The method of claim 11, wherein the radially compressing further comprises threading at least one member into the end ring, thereby radially compressing the gripping device.
 18. The method of claim 11, wherein the radially compressing further comprises the gripping device being compressed radially inward by a surface formed in the end ring, the surface encircling the base pipe.
 19. The method of claim 18, wherein the surface comprises a frusto-conical surface.
 20. The method of claim 18, wherein the gripping device comprises a surface which cooperatively engages the end ring surface, and wherein at least one of the gripping device and end ring surfaces is provided with a friction reducing material.
 21. A packer, comprising: an end ring positioned proximate a seal element on a base pipe; and a gripping device which is compressed radially inward by a surface formed in the end ring, the surface encircling the base pipe.
 22. The packer of claim 21, wherein the surface comprises a frusto-conical surface.
 23. The packer of claim 21, wherein the gripping device grips the base pipe in response to longitudinal displacement of the gripping device relative to the surface.
 24. The packer of claim 21, wherein the seal element comprises a swellable material which swells in response to contact with a fluid.
 25. The packer of claim 21, wherein the gripping device closes off a gap formed radially between the base pipe and the end ring.
 26. The packer of claim 21, wherein the gripping device comprises a circular segment having a split therein which permits radial compression of the circular segment.
 27. The packer of claim 21, wherein the gripping device comprises multiple circular segments.
 28. The packer of claim 21, further comprising a gripping surface formed on the gripping device.
 29. The packer of claim 21, further comprising at least one member which threads into the end ring and thereby radially compresses the gripping device.
 30. The packer of claim 21, wherein the gripping device comprises a surface which cooperatively engages the end ring surface, and wherein at least one of the gripping device and end ring surfaces is provided with a friction reducing material. 